As the mainstream of hearing aids develops from behind-the-ear type to smaller-sized in-the-ear type, the size of battery cells for such hearing aids is also required to be reduced accordingly. Also, since the hearing aids are used daily and continuously, the cells with longer life are desired. Button-type zinc-air cells are used as battery cells for hearing aids satisfying these requirements.
An zinc-air cell utilizes oxygen in the air as a positive electrode active material, as shown in FIG. 13A, thus a positive electrode can 51 of an zinc-air cell 50 is provided with air holes 52 for introducing air, and, as shown in FIG. 13B, these air holes 52 are sealed with a seal film 56 before use. When the zinc-air cell 50 is loaded and used in a device such as a hearing aid, the seal film 56 is removed to open the air holes 52 so that the zinc-air cell 50 starts its power generating function by using oxygen in the air introduced through the air holes 52 as the positive electrode active material.
Since a zinc-air cell employed for a minimal-sized device such as an in-the-ear type hearing aid is extremely small-sized, the replacement of such cell is very difficult. In particular, a zinc-air cell 50 involves a task to remove the seal film 56 for opening the air holes 52 before loading in a device, and this task of peeling off the small seal film 56 from the miniaturized zinc-air cell 50 is not easy. Considering the fact that principal users of hearing aids are elderly people, it will be particularly difficult for those elderly people, whose fingertip manipulation ability and eyesight have failed, to peel off the seal film 56 from the small zinc-air cell 50 and to load the small cell in a small hearing aid.
In order to facilitate the task of removing a seal film 56 and loading the zinc-air cell in a device, there has been developed a zinc-air cell 50, as shown in FIG. 14, in which one end of a seal film 53 formed to be long and hard is attached to a positive electrode can 51 to provide a sealing portion 53a, and a gripping portion 53b is provided in an extension from the sealing portion 53a (see U.S. Pat. No. 6,329,095). When the gripping portion 53 is gripped with fingertips, the zinc-air cell 50 becomes to be hung on the end of the seal film 53. In this configuration, as shown in FIG. 15, the zinc-air cell 50 can be placed in a cell receiving hole 55 of a device and the seal film 53 can be pulled up obliquely to remove the sealing portion 53a from the zinc-air cell 50, so that the tasks of loading the cell in the device and of removing the seal film can be accomplished.
The zinc-air cell 50, that can be provided for the positive electrode active material with oxygen in the atmosphere, is able to accommodate a larger quantity of a negative electrode active material, and therefore the cell capacity is approximately doubled and the service life is also approximately doubled compared to other types of cells of an identical size. Nevertheless, as for devices such as hearing aids which are to be used continuously, if the service life of the cell ends and power shutoff occurs, this directly leads to inconvenience for the user. Therefore, it is a general practice to sell a plurality of zinc-air cells in a package so as to enable users to always have a spare cell ready for replacement, and it is a general practice of the users to carry such package of cells.
The zinc-air cell 50 shown in FIG. 14 is placed in a plurality in a packaging container 60 formed by resin molding (injection molding), and a zinc-air cell packaging body thus produced, containing the plurality of zinc-air cells 50, is sold or carried.
The packaging container 60 for zinc-air cells according to the above-mentioned conventional technique, which is formed by injection molding or the like, possesses enough durability to endure long-term use. On the other hand, zinc-air cells 50 contained therein are used for a device to operate continuously and hence required to be replaced frequently. Therefore, even though containing a plurality of zinc-air cells 50, the useful period of the packaging container 60 will come to an end in a relative short period of time. For example, an zinc-air cell 50 used for hearing aides is typically required to be replaced after about 10 days of use, though depending on the mode of use and the size. Accordingly, a packaging container 60 containing six zinc-air cells 50 will become useless in about two months from the purchase. The packaging container 60 is then disposed as a waste matter even though it is still usable, which constitutes a factor of the problems of increasing waste unnecessarily and failing to exploit resources.
Further, the zinc-air cell 50 is held at their seal films 53 by protrusions 61 formed in the packaging container 60, and housed in the mounted condition in the packaging container 60. Accordingly, if the zinc-air cell 50 is subjected to vibration or shock when transported or carried, the bonding strength with the seal film 53 might be decreased, or the zinc-air cell 50 might be removed or drop off. Such problem is caused by the fact that, when exposed to shock or vibration, the seal film 53 fixed to the packaging container 60 and the zinc-air cell 50 are subjected to stress in different directions and of different magnitudes, and therefore the seal film 53 and the zinc-air cell 50 move separately from each other. If the zinc-air cell 50 is held with protrusions 61, the seal film 53 might be moved or deformed by shock or vibration, and the seal film 53 might be removed or fall off. If the seal film 53 is removed or falls off, the electrolyte will evaporate and be scattered and lost through the air holes even if the zinc-air cell 50 is contained in the packaging container 60. If such condition lasts for a long period of time, the electrolyte will be completely lost and the zinc-air cell 50 will not be usable any more. Also, even if the result is not so serious as the seal film 53 is removed or fall off, the deterioration of the bonding condition of the seal film 53 to the zinc-air cell 50 will lead to deterioration of the sealing condition of the air holes and hence deterioration of the cell properties.
An object of the present invention is to provide an inexpensive article packaging body for containing a plurality of small-sized articles such as the above-mentioned zinc-air cells to be sold or carried, and for facilitating the handling of the articles.
Another object of the present invention is to provide an article packaging body that contains a plurality of zinc-air cells each having a seal film structure designed to facilitate the loading of the zinc-air cells in a device, so that the articles are sold or carried.